A fluid will change state depending on its temperature and the external or ambient pressure. In this regard a liquid will change to a vapour when its vapour pressure becomes equal to or exceeds the external pressure acting on the liquid. Increasing the temperature of the liquid increases its vapour pressure. As a liquid changes to a vapour it absorbs energy from its surroundings. Similarly when a vapour condenses it releases energy to its surroundings and the temperature rises. Controlling the vaporisation of a liquid or the reverse process of condensation to provide a stable process is not without difficulties.
Known ways in which a liquid may be changed into a vapour include heating of the liquid and reducing the ambient pressure, by for example the direct injection of the liquid into a low-pressure chamber. However, as noted above a liquid vaporising absorbs energy and as such heat may also be required to supply the necessary energy. Alternatively a carrier gas or dilution gas can be added to the liquid or liquid/vapour mixture. This reduces the partial pressure of the vapour phase of the fluid and causes additional vaporisation. However, such devices require pumps and valves in addition to heaters. Devices with moving parts experience wear and require servicing.
It would be desirable to provide a device and method that controls a change in state of a fluid in a stable and controllable manner.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.